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Ann McDonald, a member of a local campaign against combined sewer overflows, said she has firsthand experience with the health risks that occur when sewage mixes with stormwater. After a 2024 rainstorm, she went kayaking in the Alewife Brook just outside Boston and later fell sick with diarrhea, which she linked to sewage she encountered in the water after her kayak became stuck in debris. “I got stuck in some really stinky water,” McDonald said. “I’m naive, and I thought I was above all this.”
Her account reflects the concerns raised by environmental groups as Massachusetts Water Resources Authority pursues a compromise approach to upgrading the region’s aging sewer infrastructure. Combined sewer systems carry storm runoff and sewage in the same pipes, and when the combined flow exceeds capacity during heavy storms, untreated sewage is released into nearby waterways in events called combined sewer overflows, or CSOs.
MWRA has approved a plan that critics say would keep that problem alive—at least during storm conditions that are expected to be more severe. In February, the authority’s board decided against full sewer separation, according to the story, saying separation is “relatively expensive” and could disrupt traffic and other community activities during construction. To fully separate sewers, crews would need to dig up roads and parking lots in communities, the plan’s opponents and the story’s reporting note, which can mean temporary closures.
Instead, MWRA’s proposed strategy would rely on storage tanks, partial sewer separation and infrastructure improvements intended to reduce discharges into waterways through 16 outfall pipes owned by MWRA, Cambridge and Somerville. The agency said it used precipitation projections for the year 2050 and tested three control levels: one based on a typical year of rainfall in 2050 and two modeled on eliminating sewer overflows during more intense storms. The authority ultimately chose to aim for eliminating CSOs for a typical year without the intense-storm conditions.
MWRA said its approach represents “a responsible investment of ratepayer dollars that balances real environmental benefits with actual water quality improvements,” according to a statement included in the reporting. The plan has a total price tag of $1.28 billion, with costs split among the authority, Cambridge and Somerville and passed on to ratepayers, the reporting says.
The financial and construction trade-offs are central to the dispute. The water authority estimated that eliminating CSOs during less frequent but more intense storms would cost households $82 more per year in 2050—$46 in today’s dollars—compared with its chosen target. David Stoff, who helps steer the volunteer group Save the Alewife Brook and lives near the waterway, said the proposal amounts to keeping sewage releases in place, arguing that “The plan is to keep the waters as open sewers instead of saying, ‘We’re going to rebuild the combined sewer so that sewage goes to the wastewater treatment plant and rainwater goes to the river,’” and adding that “It’s not rocket science.”
Other groups have echoed the criticism of MWRA’s February decision. Emily Norton, executive director of the Charles River Watershed Association, called the vote “abominable and embarrassing,” and said disruptions are part of the work needed to improve infrastructure. She added, “Anyone who lives in Greater Boston knows we live with construction disruptions to improve the infrastructure we rely on to live our lives.”
The reporting describes Save the Alewife Brook as an advocacy organization formed in 2020 after Arlington resident Kristin Anderson said her home flooded with raw sewage multiple times following rainstorms. The group lobbies local and state leaders for full sewer separation and for eliminating sewage discharges during storms. Another organization, the Mystic River Watershed Association, organizes volunteers to collect water samples from the brook for lab testing.
MWRA is also facing legal scrutiny tied to historic sewage pollution. The authority is listed as the defendant in two court cases dating back to the 1980s related to sewage pollution in Boston Harbor, the Charles River and the Alewife Brook, and the cases require biannual compliance reports and continued control of combined sewer overflow. The reporting says MWRA has cited an 88% reduction in CSOs across its system since the late 1980s, but it also notes that there were 23 discharges into the Alewife Brook in 2025.
The story also quotes outside experts who argue that MWRA’s planning assumptions risk falling behind changing weather patterns. Gregory Pierce, director of the Water Resources Group at UCLA, said he expects the plan to deteriorate quickly and that the authority should plan for more intense storms. “Any projection now of extreme weather events tends to be underestimated, so from how we keep breaking weather extreme records, it makes sense to build out the more expensive and comprehensive solution,” he said.
MWRA said it will submit an updated plan to state and federal environmental regulators at the end of April, with a five-month public comment period to follow. A final plan is expected in January 2027, after the review process and proposed revisions.
McDonald and other activists say they are continuing their push for more protective infrastructure even as MWRA proceeds through the regulatory timetable. She said she expects a long fight, adding that group members are trying to increase awareness through newsletters, tours of outflow pipes and cleanup events, and concluding, “I’m hopeful when I see the blue herons land here; I’m hopeful that nature will somehow inch its way along. But I think we’re far from learning how to live with the water. People see this as their living room. You got sewage in my living room? Get it out of here. Don’t tell us any more excuses. Just fix the problem.”